1. Field of the Invention
The present invention relates to a mounting structure for mounting a piezo-electric device for detecting a liquid consumption condition in a liquid container by detecting changes in an acoustic impedance and particularly detecting changes in a resonance frequency, a module having the mounting structure and the piezo-electric device, and a liquid container having the module and a container body.
2. Description of the Related Art
An ink cartridge to be mounted in an ink jet recording apparatus will be explained as an example of a liquid container of a related art. Generally, the ink jet recording apparatus has a pressure generating means for pressurizing a pressure generating chamber, a carriage mounting an ink jet recording head with nozzle openings for injecting pressurized ink as ink drops, and an ink tank for containing ink to be fed to the recording head via a flow path and is structured so as to permit continuous printing. The ink tank is generally structured as a cartridge attached to the recording apparatus in a removable state so as to be simply exchanged by a user when ink is consumed.
Conventionally, as an ink consumption control method of an ink cartridge, a method for totalizing the count of ink drops injected by the recording head and the ink amount sucked at the maintenance step of the printing head by the software and controlling the ink consumption from calculation and a method for attaching two electrodes for direct liquid level detection to the ink cartridge, detecting the point of time when ink is actually consumed in a predetermined amount, thereby controlling the ink consumption are known.
However, the method for totalizing the injection count of ink drops and sucked ink amount by the software and controlling the ink consumption from calculation imposes a problem that the pressure inside the ink cartridge and ink viscosity are varied with the use environment, for example, the magnitude of temperature and humidity in the use room, the elapsed time after opening the ink cartridge, and differences in the use frequency on the user side and an unnegligible error is caused between the ink consumption from calculation and the actual consumption. Further, there is another problem imposed that when the same cartridge is removed once and mounted again, the totalized count is reset once, so that the actual residual quantity of ink cannot be seen at all.
On the other hand, the method for controlling the point of time of ink consumption by the electrodes can detect the actual amount of ink consumption at a certain point, so that it can control the residual quantity of ink with high reliability. However, ink should be conductive so as to detect the ink level, accordingly the kind of ink to be used is limited. Further, a problem arises that the liquid tight structure between the electrodes and the ink cartridge is complicated. Furthermore, as a material of the electrodes, a noble metal which is conductive and highly corrosion-resistant is ordinarily used, so that a problem also arises that the manufacturing cost of an ink cartridge is increased. Furthermore, the two electrodes must be mounted respectively at different locations of the ink cartridge, so that a problem also arises that many manufacturing steps are required and increasing in the manufacturing cost results.
Further, as mentioned above, in the method for controlling the point of time of ink consumption by the electrodes, the holes for mounting the electrodes to the ink cartridge should be formed in the ink cartridge. Therefore, a problem also arises that when the cartridge is made of plastics, the injection molding process is complicated.
Furthermore, the electrodes have a particular sealing structure so as to keep liquid tightness, so that it is difficult to separate them from the ink cartridge. As a result, a problem also arises that it is difficult to exchange or recycle the electrodes or ink cartridge.
In order to solve the aforementioned problems, a piezo-electric device to be mounted to a liquid container and a module which can correctly detect the residual quantity of liquid and requires no complicated sealing structure are proposed.
Therefore, an object of the present invention is to provide a mounting structure for mounting a piezo-electric device having a function for detecting the consumption condition of a liquid in a liquid container to the liquid container and facilitate mounting and demounting the piezo-electric device from the liquid container.